Scroll Fluid Machine

ABSTRACT

Scroll fluid machine ( 1 ) in which the dislodgement of a slide bush ( 56 ) and a spring ( 61 ), which are provided in an eccentric bush ( 36 ), is prevented. Provided in receiving hole ( 58 ) of eccentric bush ( 36 ) are slide bush ( 56 ), which is movable in the direction of eccentricity, and spring ( 61 ), which biases slide bush ( 56 ) in a moving direction. A spring holding section ( 56   b ) and engagement projections ( 56   a ) are formed on slide bush ( 56 ). After slide bush ( 56 ) is placed in the receiving hole ( 58 ), engagement projections ( 56   a ) engage with eccentric bush ( 36 ) in a state in which slide bush ( 56 ) has been moved by the biasing force of spring ( 61 ), thus preventing slide bush ( 56 ) from falling off the receiving hole ( 58 ), and the spring holding section ( 56   b ) prevents the spring ( 61 ) from falling off the receiving hole ( 58 ).

TECHNICAL FIELD

The present invention relates to a scroll fluid machine in which a working chamber of a working fluid is formed between the wraps of a fixed scroll and a movable scroll.

BACKGROUND ART

As this type of scroll fluid machine, there has been known a single-plate type compressor-integrated expander, which includes a scroll unit composed of a movable scroll provided with a wrap provided on a base surface thereof, and a fixed scroll provided with a wrap on a base surface thereof that meshes with the wrap of the movable scroll, and in which a working chamber of the scroll unit is divided into a compression chamber and an expansion chamber by a partition, thereby forming a compression section and an expansion section (refer to, for example, Patent Document 1).

In such a scroll fluid machine, it is required to maintain an extremely small clearance between the wraps of the fixed scroll and the movable scroll, or to bring the wraps into mutual contact in an operation. If, therefore, the cores of the scrolls are misaligned due to poor component accuracy or assembly accuracy of the scrolls, a gap will occur between the wraps, resulting in significantly deteriorated performance. To avoid the problem, a structure has been developed, in which a slide bush is provided in an eccentric bush fitted in a boss of the movable scroll, the slide bush being movable in a direction of eccentricity and biased by a spring so as to prevent the misalignment of the scrolls (refer to, for example, Patent Document 2).

CITATION LIST Patent Documents

Patent Document 1: Publication of Japanese Patent No. 5209764

Patent Document 2: Publication of Japanese Patent No. 3687279

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, the eccentric bush is slidable and rotatable with respect to a fixed shaft and the movable scroll, thus posing a problem in that the slide bush or the spring provided in the eccentric bush comes off during an operation.

The present invention has been made to solve the technological problem with the prior art described above, and an object of the invention is to provide a scroll fluid machine in which the dislodgement of a slide bush and a spring biasing the slide bush, which are provided in an eccentric bush to correct misalignment, is prevented by a simple structure.

Means for Solving the Problems

To solve the problem described above, a scroll fluid machine according to the present invention includes: a scroll unit which is composed of a fixed scroll and a movable scroll each having spiral wraps formed on base surfaces of base plates thereof, the spiral wraps opposing each other, and in which a working chamber of a working fluid is formed between the wraps of the fixed scroll and the movable scroll by an orbital motion of the movable scroll about an axis of the fixed scroll; a frame having a pedestal which orbitably supports the movable scroll at an outer peripheral portion of a rear surface on the opposite side from the base surface of the movable scroll; and a support mechanism which orbitably supports the movable scroll at a central portion of the rear surface of the movable scroll, wherein the support mechanism includes: a boss provided on the rear surface of the movable scroll; an eccentric bush slidably and rotatably fitted in the boss; a slide bush placed in a receiving hole formed in the eccentric bush such that the slide bush is movable in the direction of eccentricity of the eccentric bush; a fixed shaft which is provided protruding from a bottom surface of the frame and which is slidably and rotatably inserted in an insertion hole formed in the slide bush; and a spring which is interposed between the slide bush in the receiving hole and the eccentric bush and which biases the slide bush in a direction in which the slide bush moves, a spring holding section and engagement projection which protrudes outward are formed on the slide bush, and the engagement projection engages with the eccentric bush in a state in which the slide bush has been placed in the receiving hole and then moved by a biasing force of the spring, thereby preventing the slide bush from falling off the receiving hole, and the spring holding section prevents the spring from falling off the receiving hole.

The scroll fluid machine according to the invention of claim 2 is characterized in that the receiving hole is formed passing through the eccentric bush, the engagement projections are formed on both end portions of the slide bush, and the engagement projections engage with both opening edge portions of the receiving hole of the eccentric bush in a state in which the slide bush has been moved by the biasing force of the spring in the foregoing invention.

The scroll fluid machine according to the invention of claim 3 is characterized in that the receiving hole is composed of a large-diameter section formed passing through the eccentric bush and a small-diameter section continuing from the large-diameter section in the direction of eccentricity, the engagement projections are formed on peripheral edges at both ends of the slide bush, and in a state in which the slide bush has been placed in the large-diameter section of the receiving hole and then the slide bush has been moved into the small-diameter section by the biasing force of the spring, the portions of the engagement projections positioned in the direction of the movement engage with both opening edge portions of the small-diameter section of the receiving hole, and the portions of the engagement projections positioned on the opposite side from the direction of the movement double as the spring holding section in the foregoing inventions.

The scroll fluid machine according to the invention of claim 4 is characterized in that the receiving hole is formed passing through the eccentric bush, the engagement projections are formed on the other end portion of the slide bush and engage with an opening edge portion of the receiving hole in a state in which the slide bush has been moved by the biasing force of the spring, and one end portion of the slide bush is provided with a fastener for preventing the slide bush and the spring from falling off, the fastener being positioned outside the receiving hole, in the invention of claim 1.

The scroll fluid machine according to the invention of claim 5 is characterized in that the spring holding section has a sloping surface that inclines downward toward an opening direction of the receiving hole in the foregoing inventions.

The scroll fluid machine according to the invention of claim 6 is characterized in that the scroll unit is composed of an expansion section which expands a working fluid in an expansion chamber formed between the wraps of the fixed scroll and the movable scroll thereby to orbit the movable scroll to recover motive power and a compression section which compresses the working fluid by the motive power, which has been recovered by the expansion section, in a compression chamber formed between the wraps of the both scrolls in the foregoing inventions.

The scroll fluid machine according to the invention of claim 7 is characterized in that carbon dioxide is used as the working fluid in the foregoing inventions.

Advantageous Effect of the Invention

The scroll fluid machine according to the present invention includes: a scroll unit which is composed of a fixed scroll and a movable scroll each having spiral wraps on base surfaces of base plates thereof, the spiral wraps being formed to oppose each other, and in which a working chamber of a working fluid is formed between the wraps of the fixed scroll and the movable scroll by an orbital motion of the movable scroll about an axis of the fixed scroll; a frame having a pedestal which orbitably supports the movable scroll at an outer peripheral portion of a rear surface on the opposite side from the base surface of the movable scroll; and a support mechanism which orbitably supports the movable scroll at a central portion of the rear surface of the movable scroll, wherein the support mechanism includes: a boss provided on the rear surface of the movable scroll; an eccentric bush slidably and rotatably fitted in the boss; a slide bush placed in a receiving hole formed in the eccentric bush such that the slide bush is movable in the direction of eccentricity of the eccentric bush; a fixed shaft which is provided protruding from a bottom surface of the frame and which is slidably and rotatably inserted in an insertion hole formed in the slide bush; and a spring which is interposed between the slide bush in the receiving hole and the eccentric bush and which biases the slide bush in a direction in which the slide bush moves, a spring holding section and engagement projection which protrudes outward are formed on the slide bush, and the engagement projection engages with the eccentric bush in a state in which the slide bush has been placed in the receiving hole and then the slide bush has been moved by a biasing force of the spring, thereby preventing the slide bush from falling off the receiving hole, and the spring holding section prevents the spring from falling off the receiving hole. This arrangement makes it possible to eliminate the misalignment of the scrolls by the slide bush being moved in the direction of eccentricity by the biasing force of the spring.

At this time, the spring is retained by the spring holding section formed on the slide bush, and the engagement projections also formed on the slide bush engage with the eccentric bush by the biasing force of the spring, thus preventing the slide bush from falling off. This means that it is possible to prevent the slide bush and the spring from falling off the eccentric bush by the simple machining, thus enabling the production cost to be reduced.

In this case, as in the invention of claim 2, forming the receiving hole passing through the eccentric bush, and forming the engagement projections on both end portions of the slide bush and arranging the engagement projections such that the engagement projections engage with both opening edge portions of the receiving hole of the eccentric bush in a state in which the slide bush has been moved by the biasing force of the spring make it possible to further reliably prevent the slide bush from falling off the receiving hole of the eccentric bush by the engagement of the engagement projections at both ends.

Further, the configuration according to the invention of claim 3 can also make it possible to stably retain the slide bush and the spring in the receiving hole of the eccentric bush so as to prevent the slide bush and the spring from falling off. More specifically, in the configuration, the receiving hole is composed of a large-diameter section formed passing through the eccentric bush and a small-diameter section continuing from the large-diameter section in the direction of eccentricity, the engagement projections are formed on the peripheral edges at both ends of the slide bush, and in a state in which the slide bush has been placed in the large-diameter section of the receiving hole and then moved into the small-diameter section by the biasing force of the spring, the portions of the engagement projections positioned in the direction of the movement engage with both opening edge portions of the small-diameter section of the receiving hole, and the portions of the engagement projections positioned on the opposite side from the direction of the movement double as the spring holding section.

Further, as in the invention of claim 4, the receiving hole may be formed passing through the eccentric bush, the engagement projection may be formed on the other end portion of the slide bush and engaged with an opening edge portion of the receiving hole in a state in which the slide bush has been moved by the biasing force of the spring, and one end portion of the slide bush may be provided with a fastener positioned outside the receiving hole to prevent the slide bush and the spring from falling off, the fastener being positioned outside the receiving hole. In this case, the engagement projection is required to be formed only on the other end portion of the slide bush, and the fastener is attached to one end portion of the slide bush after the spring is inserted into the receiving hole between the eccentric bush and the slide bush, thus advantageously facilitating the assembly work.

Further, as in the invention of claim 5, providing the spring holding section with a sloping surface that inclines downward toward an opening direction of the receiving hole enables the spring to be inserted into the receiving hole between the eccentric bush and the slide bush by using the sloping surface. This arrangement makes the spring installation work extremely easy.

Further, in the single-plate type scroll fluid machine, which integrates the expansion section and the compression section, as in the invention of claim 6, the foregoing inventions are especially effective in the case where carbon dioxide is used as a working fluid, as in claim 7.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal side view of a scroll fluid machine according to an embodiment to which the present invention has been applied;

FIG. 2 is a top plan view of a fixed scroll in FIG. 1, which is observed from a base surface side;

FIG. 3 is a sectional view taken on line A-A in FIG. 2;

FIG. 4 is an enlarged view of a support mechanism illustrated in FIG. 1;

FIG. 5 is a perspective view of an eccentric bush to which a slide bush illustrated in FIG. 1 has been attached (a first embodiment);

FIG. 6 is a top plan view of the eccentric bush illustrated in FIG. 5;

FIG. 7 is a sectional view taken on line B-B in FIG. 6;

FIG. 8 is a sectional view taken on line C-C in FIG. 7;

FIG. 9 is a refrigerant circuit diagram of a refrigerating cycle of the embodiment using the scroll fluid machine illustrated in FIG. 1;

FIG. 10 is a top plan view of an eccentric bush to which a slide bush according to another embodiment of the present invention has been attached (a second embodiment);

FIG. 11 is a sectional view taken on line D-D in FIG. 10;

FIG. 12 is a top plan view of an eccentric bush to which a slide bush according to a further embodiment of the present invention has been attached (a third embodiment);

FIG. 13 is a sectional view taken on line E-E in FIG. 12;

FIG. 14 is a perspective view of an eccentric bush to which a slide bush according to yet another embodiment of the present invention has been attached (a fourth embodiment);

FIG. 15 is a top plan view of the eccentric bush illustrated in FIG. 14;

FIG. 16 is a sectional view taken on line F-F in FIG. 15; and

FIG. 17 is a sectional view taken on line G-G in FIG. 16.

MODE FOR CARRYING OUT THE INVENTION

The following will describe the embodiments of the present invention in detail.

First Embodiment

(1) General Structure of a Scroll Fluid Machine 1

FIG. 1 is a longitudinal side view of a scroll fluid machine 1 according to an embodiment. The scroll fluid machine 1 according to the embodiment is, for example, a vertical single-plate type compressor-integrated expander, and used in a refrigerating cycle RC (refer to FIG. 9) of a heat pump or the like that uses carbon dioxide, which has a supercritical pressure on the high pressure side, as a refrigerant (working fluid). The refrigerating cycle RC is incorporated in an air conditioner or a heat pump type water heater (not illustrated). The configuration of the refrigerating cycle RC will be described in detail hereinafter. The scroll fluid machine 1 according to the embodiment has an expansion section 2, which performs an expanding operation by the pressure of a refrigerant and which will be discussed hereinafter, and a compression section 3 (on a low stage side), which performs a compressing operation by the expanding operation of the expansion section 2 (FIG. 2).

The scroll fluid machine 1 includes a housing 4. Provided in the housing 4 are a scroll unit 8 composed primarily of a fixed scroll 6 and a movable scroll 7 which is orbited with respect to the fixed scroll 6, a main frame (frame) 9 which orbitably supports the movable scroll 7, and a fixed shaft 11 which is fixed to the bottom surface of the main frame 9 and which is provided protruding from the bottom surface of the main frame 9.

The housing 4 is composed of a main shell 12, which is the main body, a cap-shaped top shell 13, which covers the top of the main shell 12, and a cap-shaped bottom shell 14 which covers the bottom of the main shell 12. The housing 4 is assembled by fastening the top shell 13 and the bottom shell 14 to each other by bolts, sandwiching the main shell 12 through a sealing material, such as an O-ring, and the interior of the housing 4 is hermetically sealed against the exterior. Further, the outer peripheral portion of the main frame 9 is fixed to the inner side of the main shell 12. Acting inside the hermetically sealed housing 4 is a pressure obtained by compressing a refrigerant (carbon dioxide), which has been taken in from the refrigerating cycle RC as the working fluid of the scroll fluid machine 1, by the compression section 3.

An expansion-side suction pipe 16 through which the refrigerant taken in from the refrigerating cycle RC is supplied to the expansion section 2 is connected to the top shell 13. Connected to the main shell 12 are an expansion-side discharge pipe 17 through which the refrigerant expanded by the expansion section 2 is discharged toward the refrigerating cycle RC, and a compression-side discharge pipe 18 through which the refrigerant compressed by the compression section 3 is discharged toward the refrigerating cycle RC. The ends of the expansion-side suction pipe 16 and the expansion-side discharge pipe 17 are opened to and in communication with an expansion-side suction chamber 19 and an expansion-side discharge chamber 21, respectively, which are formed in a base plate 6 a of the fixed scroll 6. The end of the compression-side discharge pipe 18 is opened into the main shell 12 and in communication with a compression-side discharge chamber 22, which is formed inside the top shell 13, through the interior of the main shell 12.

Further, a compression-side suction pipe 23 (illustrated in FIG. 3, and positioned on the front side in FIG. 1), through which the refrigerant taken in from the refrigerating cycle RC is supplied to the compression section 3, is connected to the main shell 12. The end of the compression-side suction pipe 23 is opened to and in communication with a compression-side suction chamber 24 formed in the base plate 6 a of the fixed scroll 6.

Meanwhile, a lubricant chamber 26 is formed inside the bottom shell 14, and a lubricant for lubricating the scroll unit 8 is reserved in the lubricant chamber 26. An oil feed hole 27 (FIG. 2), which passes through the base plate 6 a of the fixed scroll 6 and the main frame 9, is opened in the compression-side suction chamber 23 described above. The lubricant in the lubricant chamber 26 is fed to the compression-side suction chamber 24 through the oil feed hole 27.

Further, an oil supply passage 28 is drilled in the fixed shaft 11 along the axial direction of the fixed shaft 11. The lower end of the oil supply passage 28 is opened to the lubricant chamber 26, while the upper end is opened to the space in a boss (recess) 31, which will be discussed hereinafter.

The fixed scroll 6 is fixed to an upper surface 9 a of the main frame 9. A compression-side discharge hole 32, which will be discussed hereinafter, is formed passing through slightly closer to the center in the radial direction of the fixed scroll 6 than the foregoing compression-side suction chamber 24 of the base plate 6 a of the fixed scroll 6. An oil separator 33, which separates the lubricant in the refrigerant, is attached to the opening of the compression-side discharge hole 32 relative to the compression-side discharge chamber 22.

The movable scroll 7 is supported by a pedestal 9 b of the main frame 9 such that the movable scroll 7 is enabled to perform an orbital motion without rotating via an anti-rotation mechanism 34, such as an Oldham ring. The anti-rotation mechanism 34 is fitted in the pedestal 9 b and slidably passed through to a rear surface 7 c, which is a surface on the opposite side from a base surface 7 b of a base plate 7 a, as the movable scroll 7 performs the orbital motion. Further, the foregoing cylindrical boss 31, in which an eccentric bush 36 to be discussed hereinafter is slidably and rotatably fitted by insertion, is protrusively provided on the rear surface 7 c of the movable scroll 7.

The scroll unit 8 according to the embodiment is a so-called single-plate type scroll unit, in which both the compression section 3 and the expansion section 2 can be formed as the working chambers of a refrigerant by a pair of the fixed scroll 6 and the movable scroll 7 in the compressor-integrated expander. The fixed shaft 11 simply orbitably supports the movable scroll 7 together with the main frame 9, and the fixed shaft 11 itself is not rotatively driven.

More specifically, as illustrated in FIG. 2, an annular intermediate partition (annular wall) 38 and an annular outer partition 39 are provided in a standing manner on a base surface 6 b of the fixed scroll 6. A spiral outer fixed scroll wrap (wrap) 40 is provided in a standing manner between the intermediate partition 38 and the outer partition 39, and a spiral inner fixed scroll wrap (wrap) 41 is provided in a standing manner at a position closer to the center than the intermediate partition 38 is. Further, in the base surface 6 b, an annular groove 42, in which a seal ring (not illustrated) is fitted by insertion, is concavely provided in the edge surface of the intermediate partition 38.

In the base plate 6 a of the fixed scroll 6, the foregoing compression-side suction chamber 24 is formed on the outer circumferential end of the compression section 3 slightly toward the inner side of the outer partition 39, and the compression-side discharge hole 32 is formed on the inner circumferential end of the compression section 3 slightly toward the outer side of the intermediate partition 38. In addition, in the base plate 6 a, the foregoing expansion-side discharge chamber 21 is formed on the outer circumferential end of the expansion section 2 slightly toward the inner side of the intermediate partition 38, and the foregoing expansion-side suction chamber 19 is formed at the central portion, which is the inner circumferential end of the expansion section 2. Further, in the base plate 6 a, an annular oil groove 43 is formed slightly toward the outer side of the outer partition 39, and the foregoing oil feed hole 27 is formed in the bottom surface of a recess formed by spot facing to a predetermined depth and to a diameter that is larger than the width of the groove provided over the oil groove 43.

Meanwhile, on the base surface 7 b of the movable scroll 7, a spiral outer movable scroll wrap (wrap) 44, which meshes with the outer fixed scroll wrap 40, and a spiral inner movable scroll wrap (wrap) 46, which meshes with the inner fixed scroll wrap 41, are provided in a standing manner such that the spirals thereof are in opposite directions from each other.

According to the scroll unit 8 described above, the expansion section 2 is formed on the inner side with respect to the intermediate partition 38, and the compression section 3 is formed between the intermediate partition 38 and the outer partition 39. More specifically, as indicated by the solid line arrow in FIG. 1, the refrigerant taken in through the expansion-side suction pipe 16 is introduced into the expansion section 2 via the expansion-side suction chamber 19, and expanded in the expansion chamber (working chamber), which is formed between the wraps 41 and 46, by the scrolls 6 and 7 operating together. The volume of the expansion chamber is increased as the expansion chamber moves toward the outer peripheries of the scrolls 6 and 7, thus causing the movable scroll 7 to perform an orbital motion about the axis of the fixed scroll 6. The refrigerant subjected to the orbital motion of the movable scroll 7 passes through the expansion-side discharge chamber 21 and is discharged toward the refrigerating cycle RC outside the housing 4 through the expansion-side discharge pipe 17.

Meanwhile, the refrigerant introduced from the compression-side suction pipe 23 is taken into the compression section 3 via the compression-side suction chamber 24. As the refrigerant in the foregoing expansion chamber expands, the movable scroll 7 is caused to perform an orbital motion about the axis of the fixed scroll 6 so as to compress, by the scrolls 6 and 7 operating together, the refrigerant in the compression chamber (working chamber) formed between the wraps 40 and 44. As the orbital motion of the movable scroll 7 proceeds, the volume of the compression chamber decreases as the compression chamber moves toward the centers of the scrolls 6 and 7. Then, as the volume of the compression chamber decreases, the refrigerant that has been turned into a high-pressure refrigerant passes through the compression-side discharge hole 32 and the compression-side discharge chamber 22 and is discharged through the compression-side discharge pipe 18 toward the refrigerating cycle RC outside the housing 4.

Further, during the process, the lubricant in the refrigerant discharged through the compression-side discharge hole 32 into the compression-side discharge chamber 22 is separated from the refrigerant when the refrigerant passes through the oil separator 33, as indicated by the dashed line arrow in FIG. 1. The lubricant separated from the refrigerant passes through an oil return passage 47 formed in the main frame 9 and is reserved in the lubricant chamber 26.

The lubricant reserved in the lubricant chamber 26 is moved up through the oil supply passage 28 by the pressure difference between the lubricant chamber 26 and the compression-side suction chamber 24 and discharged from the upper end of the fixed shaft 11 so as to lubricate a bearing 49, a bearing 48 and a bearing 51, which will be discussed hereinafter. The lubricant then reaches a back pressure chamber 52 formed between the pedestal 9 b of the main frame 9 and the rear surface 7 c of the movable scroll 7, and reaches the compression-side suction chamber 24 through the oil feed hole 27.

(2) Refrigerating Cycle RC

FIG. 9 is a refrigerant circuit diagram of the refrigerating cycle RC (embodiment) using the scroll fluid machine 1 according to the present invention. In this diagram, for the sake of explanation, the expansion section 2 and the compression section 3 of the scroll fluid machine 1 are illustrated in a separated manner. The compression section 3 driven by the motive power recovered by the expansion section 2 of the scroll fluid machine 1 constitutes a low stage side compressor (a low stage side compression section) in the refrigerating cycle RC. The foregoing compression-side discharge pipe 18 of the compression section 3 is connected to a high stage side compression section 70 a driven by an electric motor 70 b of a high stage side compressor 70 positioned in a rear stage of the compression section 3.

A gas cooler 71, which cools the refrigerant, is connected to the rear stage of the compression section 70 a. The expansion section 2 and an expansion valve 72 of the scroll fluid machine 1 are connected in parallel between the outlet of the gas cooler 71 and the inlet of an evaporator 73. The refrigerant from the gas cooler 71 is taken into the expansion-side suction chamber 19 of the expansion section 2 through the foregoing expansion-side suction pipe 16. Further, the refrigerant is sent from the expansion section 2 of the scroll fluid machine 1 to the evaporator 73 through the expansion-side discharge pipe 17. Then, the refrigerant from the evaporator 73 is introduced into the compression section 3 of the scroll fluid machine 1 through the compression-side suction pipe 23.

The operation of the refrigerating cycle RC including the scroll fluid machine 1 will now be described. An intermediate pressure refrigerant (the carbon dioxide refrigerant), the pressure of which has been increased by the low stage side compression section 3 driven by the expansion section 2 of the scroll fluid machine 1, is sent through the compression-side discharge pipe 18 to the high stage side compressor 70, and the pressure thereof is further increased to a high pressure (supercritical) by the compression section 70 a driven by the electric motor 70 b. The high-pressure refrigerant is cooled by the gas cooler 71 while remaining in the supercritical state, and then a part thereof is taken into the expansion section 2 of the scroll fluid machine 1 through the expansion-side suction pipe 16 and expanded to decrease the pressure.

The rest of the refrigerant is sent to the expansion valve 72 whereby to be expanded to decrease the pressure. The expansion valve 72 is provided in order to adjust the flow rate of the refrigerant passing through the expansion section 2 of the scroll fluid machine 1.

In the expansion section 2, the refrigerant isentropically expands, causing the movable scroll 7 to perform the orbital motion, and the motive power is thereby recovered. The compression section 3 is operated as the low stage side compressor by the orbital motion of the movable scroll 7. The refrigerant expanded by the expansion section 2 is heated by the evaporator 73 (or an object is cooled thereby), and drawn into the compression section 3 of the scroll fluid machine 1 again through the compression-side suction pipe 23.

As described above, the compression section 3 of the scroll fluid machine 1 carries out a part (the low stage side) of the compression process of the refrigerating cycle RC, while the compression section 70 a of the compressor 70 on the high stage side carries out the rest (the high stage side) of the compression process. The compression power in the compression section 3 is provided by the recovered power in the expansion section 2.

(3) Back Pressure of the Movable Scroll 7

In the back pressure chamber 52 of the scroll fluid machine 1, mainly the sliding portions between the anti-rotation mechanism 34 and the pedestal 9 b and the rear surface 7 c of the movable scroll 7 are lubricated by the lubricant. Further, the interior of the housing 4 is maintained at the discharge pressure of the compression section 3 discharged into the compression-side discharge chamber 22 through the compression-side discharge hole 32 as described above, so that the lubricant maintained at a pressure close to the discharge pressure of the compression section 3 is supplied to the back pressure chamber 52 through the oil supply passage 28. Therefore, from the back pressure chamber 52, the movable scroll 7 is urged and pressed against the fixed scroll 6 under the discharge pressure of the compression section 3. The back pressure from the back pressure chamber 52 enables the smooth orbital motion of the movable scroll 7 with respect to the fixed scroll 6.

As described above, in the scroll fluid machine 1, the scroll unit 8 is driven by the expansion energy of the refrigerant, and the driving force of the scroll unit 8 generates the compression energy of the refrigerant. In this case, as described above, the fixed shaft 11 constitutes a support mechanism 54 which orbitably supports the movable scroll 7 together with the main frame 9 at the central portion of the rear surface 7 c.

(4) Configuration of the Support Mechanism 54

As specifically illustrated in FIG. 4, which is an enlarged sectional view of the support mechanism 54 of the movable scroll 7, the upper end portion of the fixed shaft 11 is inserted in an insertion hole 57 of a slide bush 56 such that the upper end portion is made slidable and rotatable by the bearing 49. The slide bush 56 is accommodated in a receiving hole 58, which is formed passing through a columnar insertion section 36 a in the axial direction thereof, the insertion section 36 a being positioned at the center of the eccentric bush 36, such that the slide bush 56 is movable in the direction of eccentricity of the eccentric bush 36. In other words, the upper end portion of the fixed shaft 11 is inserted in the eccentric bush 36 through the slide bush 56.

Further, the insertion section 36 a of the eccentric bush 36 is slidably and rotatably fitted in the boss 31 through the bearing 48. The bearing 48 receives a radial load applied to the eccentric bush 36 as the movable scroll 7 performs the orbital motion. Further, a flanged portion 36 b, which has a diameter that is larger than the diameter of the boss 31, is formed at the lower end of the insertion section 36 a of the eccentric bush 36, and a bearing 51 is provided between the flanged portion 36 b and the main frame 9. Further, a balance weight 59, which has an L-shaped section, is integrally formed on the flanged portion 36 b. The balance weight 59 is rotated in the space between the movable scroll 7 and the main frame 9 as the movable scroll 7 performs the orbital motion.

As described above, the fixed shaft 11 orbitably supports the movable scroll 7 through the intermediary of the bearing 49, the slide bush 56, the eccentric bush 36, the bearing 48, and the bearing 51. The support mechanism 54 is comprised of the boss 31, the eccentric bush 36, the slide bush 56, the fixed shaft 11, and a spring 61, which will be discussed hereinafter.

(5) Configurations of the Eccentric Bush 36, the Slide Bush 56, and the Spring 61

Referring now to FIG. 5 to FIG. 8, the eccentric bush 36, the slide bush 56, and an embodiment of the spring 61, which constitute the foregoing support mechanism 54 will be described in detail. The receiving hole 58 of the eccentric bush 36 is formed passing through the insertion section 36 a positioned at the center of the eccentric bush 36, and has a section that is longer in the direction of eccentricity of the eccentric bush 36, as illustrated in the drawings. In this case, the receiving hole 58 has a pair of flat surfaces 58 a, which extend in the direction of eccentricity and oppose each other. Further, both opening end portions of the receiving hole 58 are provided with engagement recesses 58 b, which are concavely formed at one end in the direction of eccentricity.

Meanwhile, the slide bush 56 has a substantially cylindrical shape, the receiving hole 58 described above being formed passing through the center of the slide bush 56. The bearing 49 is installed to the inner wall surface of the receiving hole 58. Both end portions in the axial direction of the receiving hole 58 of the slide bush 56 are provided with engagement projections 56 a, which are formed protruding outward and positioned at one end in the direction of eccentricity of the eccentric bush 36. Further, a spring holding section 56 b, which is recessed except both end portions in the axial direction, is formed on the other end. Further, both side walls of the slide bush 56 positioned in the direction of eccentricity of the eccentric bush 36 are formed of a pair of flat surfaces 56 c.

Further, the spring 61 is composed of a leaf spring having a sectional shape illustrated in FIG. 8, and provided in the spring holding section 56 b recessed in the slide bush 56. With the spring 61 provided in the spring holding section 56 b as described above, the slide bush 56 is installed in the receiving hole 58 formed passing through the insertion section 36 a of the eccentric bush 36. At this time, the spring 61 is first compressed to move the slide bush 56 toward the other end in the direction of eccentricity of the eccentric bush 36 and then the slide bush 56 is inserted in the receiving hole 58.

At that time, the dimension from the outer ends of the wall at both ends of the spring holding section 56 b of the slide bush 56 to the outer ends of the engagement projections 56 a is smaller than the dimension of the receiving hole 58 in that particular direction. Further, the dimension of each of the flat surfaces 56 c of the slide bush 56 is set such that each of the flat surfaces 56 c comes in slidable contact with the inner side of each of the flat surfaces 58 a of the receiving hole 58. The spring 61 is interposed between the slide bush 56 and the eccentric bush 36 in the receiving hole 58. With this arrangement, the slide bush 56 is inserted in the receiving hole 58 such that the slide bush 56 is movable in the direction of eccentricity of the eccentric bush 36.

After the slide bush 56 is placed in the receiving hole 58, when the spring 61, which has been compressed, is released, the restoring force of the spring 61 biases the slide bush 56 in the direction of eccentricity of the eccentric bush 36, causing the slide bush 56 to move in the direction of eccentricity. This in turn causes both engagement projections 56 a on one end in the direction of eccentricity to move into both engagement recesses 58 b at the opening edge portions of the receiving hole 58 of the eccentric bush 36 to engage with each other (the state illustrated in FIG. 7).

In this state, the slide bush 56 is placed in the receiving hole 58 of the eccentric bush 36 such that the slide bush 56 is movable in the direction of eccentricity of the eccentric bush 36, and the slide bush 56 is constantly biased in the direction of eccentricity of the eccentric bush 36 by the spring 61. Further, the engagement between both engagement projections 56 a of the slide bush 56 and the engagement recesses 58 b of the receiving hole 58 prevents the slide bush 56 from falling off the eccentric bush 36. In addition, the spring 61 is positioned in the spring holding section 56 b of the slide bush 56 and pressed against the eccentric bush 36, thus also preventing the spring 61 from falling off the eccentric bush 36.

Further, the upper end of the fixed shaft 11 is inserted in the bearing 49 on the inner side of the insertion hole 57 of the slide bush 56 installed to the eccentric bush 36 as described above, thus making the upper end of the fixed shaft 11 slidable and rotatable with respect to the insertion hole 57 of the slide bush 56. Reference character X1 in FIG. 2 denotes the axial center of the fixed scroll 6 and the fixed shaft 11 (the slide bush 56), and L1 in FIG. 6 denotes a line passing through the axial center X1. Reference character L2 in FIG. 6 denotes a line passing through the axial center of the movable scroll 7 and the eccentric bush 36. The difference between L1 and L2 indicates the amount of eccentricity of the movable scroll 7 with respect to the fixed scroll 6 (the same will apply to the following embodiments).

As the slide bush 56 moves in the direction of eccentricity of the eccentric bush 36 while being biased by the spring 61, thereby adjusting the amount of eccentricity of the movable scroll 7 with respect to the fixed scroll 6 and the fixed shaft 11 so as to eliminate the misalignment of the movable scroll 7 with respect to the fixed scroll 6. The dimensional relationship between the engagement projections 56 a and the engagement recesses 58 b is set such that the engagement therebetween is not released even when the slide bush 56 moves during an operation (the same will apply in the following embodiments).

As described above, the support mechanism 54 for orbitably supporting the movable scroll 7 is comprised of the boss 31 provided on the rear surface of the movable scroll 7, the eccentric bush 36 slidably and rotatably fitted in the boss 31, the slide bush 56 placed in the receiving hole 58, which is formed in the eccentric bush 36, such that the slide bush 56 is movable in the direction of eccentricity of the eccentric bush 36, the fixed shaft 11, which is provided protruding from the bottom surface of the frame 9 and which is slidably and rotatably inserted in the insertion hole 57 formed in the slide bush 56, and the spring 61, which is interposed between the slide bush 56 in the receiving hole 58 and the eccentric bush 36 and which biases the slide bush 56 in the direction in which the slide bush 56 moves. The slide bush 56 has the spring holding section 56 b and the engagement projections 56 a, which protrude outward. In the state in which the slide bush 56 has been placed in the receiving hole 58 and then the slide bush 56 has been moved by the biasing force of the spring 61, the engagement projections 56 a engage with the engagement recesses 58 b of the receiving hole 58 of the eccentric bush 36 thereby to prevent the slide bush 56 from falling off the receiving hole 58 and the spring holding section 56 b prevents the spring 61 from falling off the receiving hole 58. Thus, the misalignment of the scrolls 6 and 7 can be eliminated by the movement of the slide bush 56 in the direction of eccentricity by the biasing force of the spring 61.

At this time, the spring 61 is retained by the spring holding section 56 b formed on the slide bush 56, and the engagement projections 56 a formed also on the slide bush 56 engage with the engagement recesses 58 b formed in the receiving hole 58 of the eccentric bush 36 by the biasing force of the spring 61, thereby preventing the slide bush 56 from falling off. In other words, the simple machining, namely, forming the spring holding section 56 b in a recessed shape in the slide bush 56 and protrusively providing the engagement projections 56 a, makes it possible to prevent the slide bush 56 and the spring 61 from falling off the eccentric bush 36, thus permitting a reduction in production cost.

In particular, according to the present embodiment, the receiving hole 58 is formed passing through the insertion section 36 a of the eccentric bush 36, and the engagement projections 56 a are formed on both end portions of the slide bush 56, so that the engagement projections 56 a engage with the engagement recesses 58 b formed on both opening edge portions of the receiving hole 58 of the eccentric bush 36 in the state in which the slide bush 56 has been moved by the biasing force of the spring 61. The engagement of the engagement projections 56 a at both ends makes it possible to further reliably prevent the slide bush 56 from falling off the receiving hole 58 of the eccentric bush 36.

Second Embodiment

(6) Another Embodiment of the Slide Bush 56

Referring now to FIG. 10 and FIG. 11, another embodiment of the slide bush 56 will be described. The shapes of an eccentric bush 36 and a spring 61 are the same as those in the first embodiment (FIG. 5 to FIG. 8). A slide bush 56 in this case has a sloping surface 62, which inclines downward in the direction of the opening of a receiving hole 58 and which is formed on the wall at one end portion in the axial direction (denoted by reference numeral 56 d in FIG. 10 and FIG. 11) that constitutes a spring holding section 56 b.

Further, the wall 56 d is formed to have a low height such that the wall 56 d is shaped like an arrowhead pointing in the direction of the opening of the receiving hole 58. The rest of the configuration is the same as the configuration of the first embodiment described above. When installing the spring 61 in the spring holding section 56 b, the sloping surface 62 formed as described above enables the spring 61 to be pushed into the receiving hole 58 between the slide bush 56 and the eccentric bush 36 by making use of the sloping surface 62.

In other words, according to the present embodiment, the spring 61 can be inserted into the receiving hole 58 between the eccentric bush 36 and the slide bush 56 by making use of the sloping surface 62 of the wall 56 d after the slide bush 56 is placed in the receiving hole 58 of the eccentric bush 36. The inserted spring 61 engages with the vertical wall surface on the opposite side from the sloping surface 62 of the wall 56 d, thus preventing the spring 61 from falling off. Therefore, the slide bush 56 and the spring 61 can be assembled with great ease, as compared with the case where the slide bush 56 is placed in the receiving hole 58, with the spring 61 provided in the spring holding section 56 b, as in the foregoing embodiment.

Third Embodiment

(7) Further embodiments of the eccentric bush 36, the slide bush 56, and the spring 61

Referring now to FIG. 12 and FIG. 13, further embodiments of the eccentric bush 36, the slide bush 56, and the spring 61 will be described. In this case, a spring 61 is formed to have a circularly deformed tubular shape, as illustrated in FIG. 12. In this case also, a receiving hole 58 of an eccentric bush 36 is formed passing through in the axial direction of an insertion section 36 a. According to the present embodiment, however, the receiving hole 58 is comprised of a large-diameter section 63 a, which is a circular hole having a large inside diameter, and a small-diameter section 63 b, which is a circular hole having an inside diameter that is smaller than the inside diameter of the large-diameter section 63 a. The small-diameter section 63 b continues to the large-diameter section 63 a in the direction of eccentricity of the eccentric bush 36 (the direction in which a slide bush 56 moves). Further, engagement recesses 58 b are concavely formed in the portions corresponding to both opening edge portions of the small-diameter section 63 b.

Meanwhile, the slide bush 56 has a cylindrical shape, and engagement projections 56 a are formed on the peripheral edges at both ends in the axial direction of the slide bush 56, the engagement projections 56 a being in a flange shape projecting outward. The outside diameter of the slide bush 56 is smaller than the inside diameter of the small-diameter section 63 b of the receiving hole 58. The outside diameters of the engagement projections 56 a are sufficiently smaller than the inside diameter of the large-diameter section 63 a of the receiving hole 58 and larger than the inside diameter of the small-diameter section 63 b. Further, the inside diameters of the engagement recesses 58 b are set to be larger than the outside diameter of the engagement projections 56 a. The rest of the configuration is the same as the configurations of the embodiments described above.

Further, a spring 61 is provided in a compressed state between the engagement projections 56 a at both ends such that the spring 61 is located on the opposite side from the small-diameter section 63 b (opposite side from the moving direction), as illustrated in FIG. 13. With the spring 61 compressed between the engagement projections 56 a at both ends, the slide bush 56 is inserted into the large-diameter section 63 a of the receiving hole 58.

At this time, the outside diameters of the engagement projections 56 a of the slide bush 56 are sufficiently smaller than the inside diameter of the large-diameter section 63 a of the receiving hole 58, thus enabling the slide bush 56 to be smoothly inserted into the large-diameter section 63 a.

When the spring 61 is inserted after the slide bush 56 is placed in the receiving hole 58 as described above, the spring 61 biases, by the restoring force thereof, the slide bush 56 in the direction of eccentricity of the eccentric bush 36, thus causing the slide bush 56 to move into the small-diameter section 63 b. This in turn causes both engagement projections 56 a at one end in the direction of eccentricity to enter into both engagement recesses 58 b at the opening edge portion of the small-diameter section 63 b to engage with each other (the state illustrated in FIG. 12 and FIG. 13).

In this state, the slide bush 56 is placed in the receiving hole 58 of the eccentric bush 36 such that the slide bush 56 is movable in the direction of eccentricity of the eccentric bush 36, and the slide bush 56 will be constantly biased in the direction of eccentricity of the eccentric bush 36 by the spring 61. Further, both engagement projections 56 a of the slide bush 56 engage in the engagement recesses 58 b of the small-diameter section 63 b, thus preventing the slide bush 56 from falling off the eccentric bush 36. Further, the spring 61 is positioned between the engagement projections 56 a on the opposite side from the small-diameter section 63 b of the slide bush 56 and pressed relative to the eccentric bush 36, thus also preventing the spring 61 from falling off the eccentric bush 36.

As described above, according to the third embodiment, the receiving hole 58 is composed of the large-diameter section 63 a formed passing through the eccentric bush 36, and the small-diameter section 63 b, which continues to the large-diameter section 63 a in the direction of eccentricity, and the engagement projections 56 a are formed on the peripheral edges at both ends of the slide bush 56. After the slide bush 56 is placed in the large-diameter section 63 a of the receiving hole 58 and the slide bush 56 is moved in the small-diameter section 63 b by the biasing force of the spring 61, the portions of the engagement projections 56 a positioned in the direction of the movement engage with the engagement recesses 58 b formed in both opening edge portions of the small-diameter section 63 b of the receiving hole 58, and the portions of the engagement projections 56 a positioned on the opposite side from the direction of the movement double as a spring holding section that retains the spring 61. This arrangement enables the slide bush 56 and the spring 61 to be stably retained in the receiving hole 58 of the eccentric bush 36, thus preventing the slide bush 56 and the spring 61 from falling off. In addition, the slide bush 56 is cylindrical, thus leading to a reduction in machining cost.

Fourth Embodiment

(8) Further Additional Embodiments of the Eccentric Bush 36, the Slide Bush 56, and the Spring 61

Referring now to FIG. 14 to FIG. 17, further additional embodiments of the eccentric bush 36, the slide bush 56, and the spring 61 will be described. In the present embodiments, an elliptical receiving hole 58 having the same diameter as that of the small-diameter section 63 b of the third embodiment illustrated in FIG. 12 and FIG. 13 is formed in an insertion section 36 a of an eccentric bush 36. The elliptical receiving hole 58 is longer in the direction of eccentricity of the eccentric bush 36. Further, the engagement projection 56 a around one end portion in the axial direction of the slide bush 56 has been eliminated. Instead, one end portion of the slide bush 56 in the axial direction protrudes out of a receiving hole 58, as illustrated in FIG. 16. Further, a groove 64 is concavely formed around the protruding portion. A C-shaped fastener (clip) 66 illustrated in FIG. 14 and FIG. 15 is fitted in the groove 64. Further, the engagement recess 58 b at one end in the axial direction of the receiving hole 58 of the eccentric bush 36 is not provided. The rest of the configuration is the same as the configurations of the embodiments described above.

Further, in the case of the present embodiment, the slide bush 56 is first inserted in the receiving hole 58 from the other end side of the receiving hole 58 without installing a spring 61. After that, the spring 61 is inserted from one end side in the axial direction in a compressed state between the engagement projection 56 a at the other end and the groove 64 such that the spring 61 is located on the opposite side from the moving direction, as illustrated in FIG. 17. After the spring 61 is inserted, the restoring force of the spring 61 biases the slide bush 56 in the direction of eccentricity of the eccentric bush 36, and the slide bush 56 is therefore moved, thus causing the engagement projection 56 a at one end side in the direction of eccentricity to enter and engage with the engagement recess 58 b at the opening edge portion (the state illustrated in FIG. 16).

In the state in which the spring 61 has been inserted as described above, the groove 64 of the slide bush 56 is located outside the receiving hole 58. In this state, a fastener 66 is fitted to the groove 64. This causes the fastener 66 to engage with the eccentric bush 36 at one end side in the axial direction of the slide bush 56, and this engagement is not released even when the slide bush 56 moves. Further, since the fastener 66 is positioned at one end side of the spring 61, the fastener 66 constitutes a spring holding section jointly with the engagement projection 56 a positioned on the other end side. This arrangement prevents the slide bush 56 and the spring 61 from falling off.

As described above, the receiving hole 58 is formed passing through the eccentric bush 36, the engagement projection 56 a is formed on the other end portion of the slide bush 56 and arranged so as to engage with the engagement recess 58 b at the opening edge portion of the receiving hole 58 in the state in which the slide bush 56 has been moved by the biasing force of the spring 61, and the fastener 66 for preventing the slide bush 56 and the spring 61 from falling off is installed at one end portion of the slide bush 56 such that the fastener 66 is positioned outside the receiving hole 58. Therefore, the engagement projection 56 a is required to be formed only on the other end portion of the slide bush, and the fastener 66 can be attached to one end portion of the slide bush 56 after the spring 61 is inserted in the receiving hole 58 between the eccentric bush 36 and the slide bush 56. Thus, the assembly work becomes easier.

In the embodiments, the present invention has been applied to the so-called single-plate type compressor-integrated scroll expander taken as an example of the scroll fluid machine; however, the inventions of claim 1 to claim 5 are not limited thereto. The present invention is effective also for a scroll fluid machine or the like in which an expansion section and a compression section are connected by a drive shaft.

DESCRIPTION OF REFERENCE NUMERALS

-   -   1 Scroll fluid machine     -   2 Expansion section     -   3 Compression section (Low stage side)     -   6 Fixed scroll     -   7 Movable scroll     -   8 Scroll unit     -   9 Main frame     -   11 Fixed shaft     -   31 Boss     -   36 Eccentric bush     -   40, 41, 44, 46 Wrap     -   49 Bearing     -   54 Support mechanism     -   56 Slide bush     -   56 a Engagement projection     -   57 Insertion hole     -   58 Receiving hole     -   58 b Engagement recess     -   61 Spring     -   63 a Large-diameter section     -   63 b Small-diameter section     -   66 Fastener     -   RC Refrigerating cycle 

1. A scroll fluid machine comprising: a scroll unit which is composed of a fixed scroll and a movable scroll each having spiral wraps formed on base surfaces of base plates thereof, the spiral wraps opposing each other, and in which a working chamber of a working fluid is formed between the wraps of the fixed scroll and the movable scroll by an orbital motion of the movable scroll about an axis of the fixed scroll; a frame having a pedestal which orbitably supports the movable scroll at an outer peripheral portion of a rear surface on the opposite side from the base surface of the movable scroll; and a support mechanism which orbitably supports the movable scroll at a central portion of the rear surface of the movable scroll, wherein the support mechanism includes: a boss provided on the rear surface of the movable scroll; an eccentric bush slidably and rotatably fitted in the boss; a slide bush placed in a receiving hole formed in the eccentric bush such that the slide bush is movable in a direction of eccentricity of the eccentric bush; a fixed shaft which is provided protruding from a bottom surface of the frame and which is slidably and rotatably inserted in an insertion hole formed in the slide bush; and a spring which is interposed between the slide bush in the receiving hole and the eccentric bush and which biases the slide bush in a direction in which the slide bush moves, a spring holding section and engagement projection which protrudes outward are formed on the slide bush, and the engagement projection engages with the eccentric bush in a state in which the slide bush has been placed in the receiving hole and then moved by a biasing force of the spring, thereby preventing the slide bush from falling off the receiving hole, and the spring holding section prevents the spring from falling off the receiving hole.
 2. The scroll fluid machine according to claim 1, wherein the receiving hole is formed passing through the eccentric bush, the engagement projections are formed on both end portions of the slide bush and the engagement projections engage with both opening edge portions of the receiving hole of the eccentric bush in a state in which the slide bush has been moved by the biasing force of the spring.
 3. The scroll fluid machine according to claim 1 or 2, wherein the receiving hole is composed of a large-diameter section formed passing through the eccentric bush and a small-diameter section continuing from the large-diameter section in the direction of eccentricity, the engagement projections are formed on peripheral edges at both ends of the slide bush, and in a state in which the slide bush has been placed in the large-diameter section of the receiving hole and then the slide bush has been moved into the small-diameter section by the biasing force of the spring, the portions of the engagement projections positioned in the direction of the movement engage with both opening edge portions of the small-diameter section of the receiving hole, and the portions of the engagement projections positioned on the opposite side from the direction of the movement double as the spring holding section.
 4. The scroll fluid machine according to claim 1, wherein the receiving hole is formed passing through the eccentric bush, the engagement projection is formed on the other end portion of the slide bush and engages with an opening edge portion of the receiving hole in a state in which the slide bush has been moved by the biasing force of the spring, and one end portion of the slide bush is provided with a fastener for preventing the slide bush and the spring from falling off, the fastener being positioned outside the receiving hole.
 5. The scroll fluid machine according to claim 1, wherein the spring holding section has a sloping surface that inclines downward toward an opening direction of the receiving hole.
 6. The scroll fluid machine according to claim 1, wherein the scroll unit includes: an expansion section which expands a working fluid in an expansion chamber formed between the wraps of the fixed scroll and the movable scroll thereby to orbit the movable scroll to recover motive power; and a compression section which compresses the working fluid by the motive power, which has been recovered by the expansion section, in a compression chamber formed between the wraps of the both scrolls.
 7. The scroll fluid machine according to claim 1, wherein carbon dioxide is used as the working fluid. 